1. Field
The present invention pertains generally to communications, and more specifically to a method and apparatus for channel sensitive scheduling of transmissions in a communication system.
2. Background
Communication systems, and wireless systems in particular, are designed with the objective of efficient allocation of resources among a variety of users. Wireless system designers in particular aim to provide sufficient resources to satisfy the communication needs of its subscribers while minimizing costs. Various scheduling algorithms have been developed, each based on a predetermined system criteria.
In a wireless communication system employing a Code Division-Multiple Access (CDMA) scheme or Wideband Code Division Multiple Access (WCDMA) one scheduling method assigns each of the subscriber units code channels at designated time intervals on a time multiplexed basis. A central communication node, such as a Base Station (BS) or Node B, implements the unique carrier frequency or channel code associated with the subscriber to enable exclusive communication with the subscriber. TDMA schemes may also be implemented in landline systems using physical contact relay switching or packet switching. A CDMA system may be designed to support one or more standards such as: (1) the “TIA/EIA/IS-95-B Mobile Station-Base Station Compatibility Standard for Dual-Mode Wideband Spread Spectrum Cellular System” referred to herein as the IS-95 standard; (2) the standard offered by a consortium named “3rd Generation Partnership Project” referred to herein as 3GPP; and embodied in a set of documents including Document Nos. 3G TS 25.211, 3G TS 25.212, 3G TS 25.213, and 3G TS 25.214, 3G TS 25.302, referred to herein as the W-CDMA standard; (3) the standard offered by a consortium named “3rd Generation Partnership Project 2” referred to herein as 3GPP2, and TR-45.5 referred to herein as the cdma2000 standard, formerly called IS-2000 MC, or (4) some other wireless standard. A WCDMA system may be designed to support one of more of the same standards listed above for a CDMA system.
WCDMA is an interference-limited system, which means that neighboring cells and other users limit the uplink and downlink capacity of any single cell. To maximize capacity, interference (other signal power) should be minimized. This includes minimizing signal-to-interference (Eb/No) requirements, minimizing overhead channel power, and minimizing control-only channel power. In addition, good phone performance includes long battery life. To achieve this goal, the phone should minimize its power during dedicated channel transmission and monitoring of overhead channels.
Accordingly, there is a need for a method and apparatus for channel sensitive scheduling of transmissions in a communication system with application to multiple classes of users.